How does a petrol car performance compare to a diesel car?

But, Diesel engines often use a far high compression ratio than petrol engines due to the nature of the fuel they use, combined with the fact that modern car engines operate closer to a 'combined' cycle (between the Otto and Diesel engines) which leads to Diesel engines actually having a higher efficiency in practise. read more

As an example, the Fiat 500 diesel does nearly 14mpg more than its 1.2 petrol sister, but its purchase price is £2400 higher. On economy alone, owners would need to cover more than 130,000 miles in the diesel before the fuel economy/purchase price equation levels out. read more